The invention relates to a tool head for use in machine tools comprising a base body coupled to a machine spindle, comprising at least one tool-receiving means for a cutting tool, and comprising a rotatable slide mechanism, which eccentrically carries the tool-receiving means, and is rotated about an eccentric axis parallel to the base-body axis with respect to the base body in order to facilitate an adjusting of the cutting radius of the cutting tool.
A tool head of this type is known from DE-A 197 02 219, in which a rotatable slide mechanism is provided, which is arranged near the center in the base body, and which can be adjusted through centrally arranged transmission elements. The external machining of elongated workpieces is not easily possible with this tool head.
Starting out from this, the basic purpose of the invention is to provide a tool head which is compact and lightweight, and with which also elongated workpieces can be machined with a high rotating speed.
The basic concept of the solution of the invention is that a second rotatable slide mechanism is provided, which carries a second tool-receiving means, and is rotated about a second eccentric axis parallel to the base-body axis with respect to the base body in order to facilitate an adjusting of the cutting radius of the respective cutting tool. A preferred embodiment of the invention provides that transmission means are arranged in the base body, which transmission means are coupled to both rotatable slide mechanisms so that they can be driven together with the adjustment of the reciprocal distance between the two cutting tools. The transmission means can advantageously be coupled to an additional machine spindle and can be driven by a machine located drive motor. It is fundamentally possible to drive the transmission means also with a drive motor integrated into the base body. The drive motor can thereby be configured as a stepping motor or as a servomotor. The transmission means have advantageously a speed-reduction gearing configured as a harmonic-drive or planetary transmission.
According to a further preferred embodiment of the invention, the two rotatable slide mechanisms are arranged diametrically opposite one another with reference to the base-body axis, and are adjusted radially oppositely directed through the common transmission means.
A further preferred embodiment of the invention provides that the base body has an axially central through opening, and that the transmission means form a hollow-shaft unit enclosing the through opening.
A preferred embodiment provides that the rotatable slide mechanisms each have an eccentric disk which is supported axially parallel eccentrically in the base body, which are axially adjacent to one another, and extend with axially parallel crank arms which carry the tool-receiving means, through a front opening of the base body. The outermost eccentric disk, which is adjacent to the front facing side of the base body, has thereby advantageously an opening for passage of the crank arm of the innermost eccentric disk. Since the crank arms carry out a circular motion about the base-body axis during operation of the rotatable slide mechanisms, the front-facing openings of the base body are configured as elongate holes preferably curved in their longitudinal extent. In order to cover the slotted holes, the tool-receiving means can carry outside shields. The opening in the outermost eccentric disk must have sufficient play of movement for the crank arm of the innermost eccentric disk, and is therefore advantageously also configured as a slotted hole.
A further advantageous development of the invention provides that the transmission means is coupled to the eccentric disks of the rotatable slide mechanisms through a common disk clutch concentrically supported in the base body. A particularly compact design is achieved when the eccentric disk and the disk clutch are arranged sandwichlike axially side-by-side in the base body. The disk clutch engages advantageously with two eccentrically arranged, axially parallel projecting keylike clutch members received in a respective one of the clutch grooves of the two eccentric disks. The clutch members form thereby a type of gear teeth which are moved along the clutch grooves during rotation of the disk clutch taking along the eccentric disks. The clutch member for the outmost eccentric disk extends through an opening of the innermost eccentric disk, which opening is preferably configured as a slotted hole.
In order to keep the center of the tool head free for passage of a workpiece or a sleeve, the eccentric disks and the disk clutch have also an opening surrounding the through opening. The eccentric disks of the rotatable slide mechanisms are advantageously supported in radial roller bearings, which are preferably configured as needle bearings, in the base body. Also the disk clutch can be supported in axial and/or radial roller bearings in the base body. The eccentric disks, which rest sandwichlike against one another, the disk clutch and the front-side base body lid are advantageously supported against one another through axial slide or roller bearings. In the case of slide bearings, the respective parts can be provided with a friction-reducing coating.
According to a preferred or alternative development of the invention, it is possible to provide a calibrating mechanism in order to calibrate the zero position of the at least one rotatable slide mechanism or a linear slide mechanism, which calibrating mechanism includes preferably a calibration counter arranged in the base body, which counter can be operated, for example, by a trip cam arranged on the driven side of the transmission means, the disk clutch or on one of the eccentric disks, and emits a calibrating signal to an external electronics of the calibrating mechanism. The calibrating mechanism can furthermore have an external microprocessor arrangement, which houses at least one electronically callable calibrating table or calibrating curve for the coordination of the relative rotation of the two spindles and the cutting radius.
A shifting of the masses does not result from the rotation of the rotatable slide mechanisms so that balancing masses are not needed. However, attention must be paid, when using rotatable slide mechanisms that during the adjusting operation, to not only the distance of the blades from the base-body axis that is changed but also the alignment of the blades with respect to the axis of rotation. For many cases of application this is indeed of a subordinate importance. An improvement in this respect can, however, be achieved in such a manner that the two tool-receiving means can be adjusted in dependency of the respective angle of rotation of the rotatable slide mechanism or of the cutting radius with a finite alignment of the cutting tool relative to the base-body axis with respect to the rotary body (compare DE-A 197 02 219). The tool-receiving means can be adjusted for this purpose by aligning a reference plane associated with the cutting tool with the base-body axis and with respect to the respective rotatable slide mechanism. In order to make this possible, it is suggested according to a preferred development of the invention that the tool-receiving means are arranged rotatably about an axis parallel to the eccentric axis of the rotatable slide mechanism in an eccentric bore of the respective rotary slide.
The tool head of the invention is particularly suited for the external machining, in particular for turning, cutting or contour turning of elongated workpieces received in the central through opening, in that the two cutting tools, which are diametrically opposite one another with respect to the through opening, are adjusted at their radial distance from one another by a common operation of the rotatable slide mechanisms.
A further advantageous use of the tool head of the invention is that the workpiece to be machined can be supported with respect to the center of the tool head end of the machine spindle.
The tool head of the invention can furthermore be advantageously utilized for receiving a sleeve in the center through opening for centering of a workpiece to be machined. The tool head of the invention is particularly suited for use in a machine tool with a double spindle, which has two spindles arranged concentrically to one another, and can be driven independently of one another.